Doepfer A-111-4 Quad VCO

A-111-4 contains four precision VCOs and has individual controls, inputs and outputs for each VCO available as well as a common control and output unit. After all the A-111-4 is very similar to four A-111-3 without LFO mode but built in output mixers for the three waveforms, and a master unit for all four VCOs.

Controls, inputs and outputs for each of the four VCOs:

1V/Octave CV input

Octave switch (+1 / 0 / -1 octave)

Tune control (range internally adjustable by jumpers: ~ 2 semitones / ~ 1 octave / ~ 4 octaves)  

Modulation CV input

Modulation destination:

upper position: exponential frequency modulation (XM)

lower position: linear  frequency modulation (LM) or pulsewidth modulation of the rectangle (PM), selectable via internal jumper

Frequency Modulation (FM) or Pulsewidth Modulation of the rectangle (PWM)

Modulation intensity

Triangle output, about 5 Vpp level (-2.5V ... +2.5V)

Sawtooth output, about 5 Vpp level (-2.5V ... +2.5V)

Rectangle output (about 50% without external PWM), about 5 Vpp level (-2.5V ... +2.5V)

Sync input (hard or soft sync internally selectable via jumper, CEM3340 hard sync type, see technical remarks below)

min. 10 octaves range (with appropriate external CV)

CEM3340 based VCO (triangle core)

each VCO has it's own separate internal +/- power supply for each for best stability and the prevention of unwanted synchronisation of the VCOs

Controls, inputs and outputs of the master section:

1V/Octave CV input

Octave switch (+1 / 0 / -1 octave)

Tune control (range internally adjustable by jumpers: 2 semitones / 1 octave / 4 octaves)  

Frequency Modulation CV input (FM)

FM intensity

Triangle sum output, about 15 Vpp level

Sawtooth sum output, about 15 Vpp level

Rectangle sum output, about 15 Vpp level

as soon as the single waveform output of a VCO is patched this waveform of the VCO in question is removed from the sum (this function can be turned off for each single output socket by means of solder brigdes on the pc board, i.e. the sum contains then all signals independent of the patching of the single output)

CV output (outputs the sum CV that is used to control all four VCOs)

bus CV (via jumper, optional, please remove the bus jumper if this feature is not used to avoid unwanted frequency modulation as then the unused CV line of the bus works as a kind of antenna)

Typical applications:

fat sounding monophonic VCO with the possibility to adjust any intervals

paraphonic patches in combination with the polyphonic CV interface A-190-5 (all four VCOs processed by one VCF/VCA)

full polyphonic patches in combination with the polyphonic CV interface A-190-5 and four complete VCF/VCA sections  

complex VCO patches with up to four VCOs by means of the frequency modulation features (exponential an linear) and the sync functions